Ceramic matrix composite (CMC) materials are more commonly being used for various high temperature applications. For example, because CMC materials can withstand relatively extreme temperatures, there is particular interest in replacing components within a combustion gas flow path of a gas turbine engine with components made from CMC materials. Typically, CMC materials comprise ceramic fibers embedded in a matrix material such as silicon carbide (SiC), silicon, silica, alumina, or combinations thereof. Plies of the CMC material may be laid up to form a preform component that may then undergo thermal processing, such as a cure or burn-out to yield a high char residue in the preform, and subsequent chemical processing, such as melt-infiltration with silicon, to arrive at a component formed of a CMC material having a desired chemical composition.
Damaged CMC components can be difficult to repair. For example, typical CMC repairs utilize repair plugs made from a stack of CMC plies, and for small CMC parts requiring small repair plugs, it may be difficult to stack plies to form a small repair plug. Further, the ceramic fibers within the repair plug may not optimally align with the stress orientation of the CMC component, particularly in a CMC component operating in a multidirectional load path environment, where the local stress state at the area to be repaired varies from the global stresses for which the component's architecture was designed. As such, the repair plug may not be able to control stresses along one or more load paths. Moreover, some CMC materials may not be suitable for all methods of processing a CMC repair patch with the CMC component. As an example, some processes for densifying CMC materials such as melt infiltration require temperatures that would attack, degrade, or essentially burn up individual CMC fibers such that using individual randomly oriented CMC fibers may be unfeasible. As another example, melt infiltration may produce voids in the intertow regions of CMC materials utilizing woven fibers rather than substantially unidirectional fibers, such that the use of such woven fiber CMC repair patches may be undesirable.
Accordingly, CMC repair patches and methods for repairing CMC components that overcome one or more shortcomings of typical repairs would be desirable. For example, a repair patch utilizing unidirectional CMC plies that provides more alignment options for repairing a CMC component operating in a multidirectional load path environment would be beneficial. In particular, a repair patch utilizing randomly oriented unidirectional CMC plies would be useful. Additionally, a repair patch utilizing unidirectional CMC plies in which the CMC plies are oriented such that ceramic fibers of the plies extend in a plurality of directions would be helpful. Further, methods for repairing CMC components utilizing randomly oriented unidirectional CMC plies would be advantageous.